Give him time bud, his whole life has been turned upside down. He's in a place he's never been too, doesn't know anybody, and as @PaulB would say, he doesn't even have supermodels to look at.
If your water parameters are good and the rest of your tank is good, enough hiding place, enough space etc.. he will acclimate and be merry (Hopefully) and feast with the rest of his new family.